Footnotes for Unit 12 - Earth's Changing Climate

Water vapor contributes to climate change through an important positive feedback loop: as the atmosphere warms, evaporation
from Earth's surface increases and the atmosphere becomes able to hold more water vapor, which in turn traps more thermal
energy and warms the atmosphere further. It also can cause a negative feedback when water in the atmosphere condenses into
clouds that reflect solar radiation back into space, reducing the total amount of energy that reaches Earth. For more details,
see National Oceanic and Atmospheric Administration, "Greenhouse Gases: Frequently Asked Questions,"
http://lwf.ncdc.noaa.gov/oa/climate/gases.html.